Slide 1

Powder Compaction

Dr.R.Narayanasamy,B.E.,M.Tech.,M.Engg.,Ph.D.,(D.Sc) Professor, Department of Production Engineering ,National Institute of Technology,Tiruchirappalli - 620015,Tamil Nadu, India.Email ids: narayan@nitt.edu&narayan10455@yahoo.co.in

By

Steps in Making Powder Metallurgy Parts

Outline of processes and operations involved in making powder-metallurgy parts.Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.ISBN 0-13-148965-8. 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Powder compaction methodsUnidirectional (die) pressing: Single action pressingDouble action pressingIsostatic pressingPowder rollingStepwise pressingPowder extrusion: powder direct; powder cannedPowder swagingExplosive compactingPowder forging

Die compactionConsolidation of powder by the application of uniaxial stress while the powder is constrained in rigid tooling.Powders from the feed hopper at apparent density in placed in die cavity.Particles rearrange, deform and bond because of pressure applied by punch.Deformation hardens the particles and hence, more pressure is applied to the powder.After attaining maximum hardness, there is no density change with further application of compaction pressure.The compaction pressure ranges up to 1000MPa. (Depends on powder and tool material)Soft powders (ex: Al powders attains more green density (~90%) with less compaction pressure ~ 150 MPa)Hard powders (ex: cemented carbide attains ~ 60% green density for the compaction pressure of ~175MPa).

Die compaction process

Green Compaction tool for P/M(Uni directional compaction)

Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.ISBN 0-13-148965-8. 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.Compaction(a) Compaction of metal powder to form a bushing. The pressed-powder part is called green compact. (b) Typical tool and die set for compacting a spur gear. Source: Courtesy of Metal Powder Industries Federation.

Parts Made by Powder-Metallurgy

(a) Examples of typical parts made by powder-metallurgy processes. (b) Upper trip lever for a commercial sprinkler made by P/M. This part is made of an unleaded brass alloy; it replaces a die-cast part with a 60% savings. (c) Main-bearing metal-powder caps for 3.8 and 3.1 liter General Motors automotive engines. Source: (a) and (b) Reproduced with permission from Success Stories on P/M Parts, 1998. Metal Powder Industries Federation, Princeton, New Jersey, 1998. (c) Courtesy of Zenith Sintered Products, Inc., Milwaukee, Wisconsin.a)b)c)Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.ISBN 0-13-148965-8. 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.

Conventional P/M RouteCompaction relative density R=(f /th) > 0.70 (or) 70%

During sintering, there is 4 to 5% increase in R

During cold working, (Example: Cold upsetting) there is 12% increase in R

During hot working, there is more than 20% increase in R

(a)(b)(a)(b)Pressures mobilized during single action die compaction, a) without and b) with lubricant.Pressures mobilized during a) free mould (wet bag) and b) fixed mould (dry bag) isostatic compaction.

Schematic of experimental triaxial compaction chamber

Unidirectional compaction: Single action pressingVertical pressure is applied to powderFriction occurs between powder and die wallsNon uniform pressure distribution along sides of compactsPressure gets reduced at the base of compacts.

Unidirectional compaction: Double action pressingProduce equal pressure at top and bottom of compactsFriction in side walls are reduced by lubricants which enhances the lateral pressureFinal global stress state is not uniformParts with large height to diameter ratios and complex shapes cannot be compacted But, used in where large production rates are required

Isostatic compaction/ Hydrostatic compactionPowder is placed in a flexible mould (rubber) and immersed into a pressure vessel and compacted using hydorstatic pressureThis method is flexible with part size and shapeThe final global stresses are isostatic around the compactsThe production rate is low. To overcome this, a slight modification with fixed mould (upper and lower end with rigid part) and side walls with rubber was introducedThis modified setup leads to low axial pressure than lateral pressure

Triaxial compactionSetup is similar to fixed mould isostatic pressing Lateral and axial pressures can be controlled separatelyShear stress within compacts enhance green density and strengthTorsional shear stress is applied (either by load piston or rotation of tool)The minor principal stress (3) is uniform in all directionsAxial pressure is applied by the piston which increases axial stress (1)The resulting principal stress difference (1 - 3 = 2) The above is nothing but Tresca Yield criteria

Mohr stress space diagrams In fig. (a), confining pressure is increased to produce 3 in all directions (horizontal dotted line)Axial stress (1) is increased along with increase in average normal stress and also produce a shear stress (angular dotted line)The various combinations of stress paths are shown in fig. (b).Stress path (1) reduces total time of compaction with low green density compared to other stress paths.Stress path (5) produces high green density compacts with high confining pressure than other stress paths.Stress path (3) is the representation of fig.(a) which is optimum.There is a limit for shear stress for compaction in rigid moulds. Further increase in shear stress will lead to shear failure.A failure plane propagation is approximately 45

Stress and volumetric strain versus axial strain response curves for green iron compacts at various confining pressures.The peak stress in each curve denotes shear failure.Increasing confining pressure increases the principal stress difference (shear stress). Hence, the samples shear strength is increased.Axial strain at failure increases with decreasing confining pressure.As the difference between principal stresses increases, the axial strain at failure also increases.Modulus of elasticity increases with increasing confining pressure.Green density also increases with increasing in confining pressure.Volume decrease is high when the compacts have low green density (or) the difference between principal stresses decreases.Under shear stress, different types of iron powders behave similarly.

132

311

3

2

Mohrs circle representation of a three-dimensional state of stress.2

Mohrs circle (three dimensional) for the state of stress Uniaxial tension

- 1 max=1/ 2

2 = 3 = 0(a)

132

Mohrs circle (three dimensional) for the state of stress Uniaxial compression

1 = 2 = 03 max

321

Mohrs circle (three dimensional) for the state of stress biaxial tension

3 = 0 2 1 max = 2 1 3

31 2 1 = 22

Mohrs circle (three dimensional) for the state of stress biaxial compression

1 3 = 0 1 3

1 2 2 3 max = 2

1 = 22

Mohrs circle (three dimensional) for the state of stress triaxial tension (unequal)

1 2 = 3 max = 2 =3

1 3 2 1 = 2 2 = 23

Mohrs circle (three dimensional) for the state of stress triaxial compression (unequal)

2 = 3 1

max = 2 =3

1 2 3

Mohrs circle (three dimensional) for the state of stress uniaxial tension plus biaxial compression

2 = 3 1 max = 2 =3

3 2 1 1 = -2 2 = -23

Failure envelope on Mohr stress space for green iron compactsCurve drawn tangent to Mohrs circles indicates the failure envelope.Above this shear stress, failure takes place by shear.The failure envelope is in a linear pattern with approximately 5 angle to the horizontal line.This is in good agreement with Schwartz et al.In empirically fitted log-log sheet, the equation of failure curve is = 3.52 ^ 0.48 where shear stress and normal stress.

ISOSTATIC DENSITY AT 100 ksi = 90.4%PERCENTAGE THEORITICAL DENSITY SHEAR STRESS , ksi020406080100120 PRINCIPAL STRESS DIFFERENCE 1 3 , ksi

For decreasing confining pressure

EDGECTR.EDGEISOSTATIC AT 30,000 psiGREEN DENSITYGREEN DENSITYISOSTATIC AT 60,000 psiEDGECTR.EDGERadial density gradients of isostatically compacted iron powder at different levels of confining pressure. (1 ksi = 6.9 MPa.)

EDGECTR.EDGERadial density gradients of triaxially compacted iron powder at different levels of confining pressure. (1 ksi = 6.9 Mpa.)GREEN DENSITYTRIAXIAL AT 30,000 psiTRIAXIAL AT 60,000 psiEDGECTR.EDGE

Radial density gradients of isostatically and triaxially compacted iron powder at different levels of confining pressureAtomized iron powder was used in this study.Radial density variation was measured by subsequently machining the compacts up to the core.At 30,000 psi, Isostatic compact has high density at edge than centre (variation: ~ 0.23g/cm^3).Particles closer to the edge are plastically deformed and compacted compared to the core.At 60,000 psi, Isostatic compaction shows less density variation (~ 0.10 g/cm^3) across the radial distance. At 30,000 psi, triaxial compaction shows same tendency with density variation of ~ 0.19 g/cm^3.At 60,000 psi, triaxial compaction shows no density variation across the radial distance.

Vertical density gradients of isostatically compacted iron powder at different levels of confining pressure. (1 ksi = 6.9 Mpa.)

Vertical density gradients of triaxially compacted iron powder at different levels of confining pressure. (1 ksi = 6.9 Mpa.)

Vertical density gradients of isostatically and triaxially compacted iron powder at different levels of confining pressureVertical density variation was obtained by sectioning the compacts horizontally.At 30,000 psi, isostatic compaction shows high density at centre than top and bottom with a density variation of ~0.2 g/cm^3.At 60,000 psi, isostatic compaction shows density variation of ~0.15g/cm^3At 30,000 psi, triaxial compaction shows higher overall density with less variation of density between top and bottom.At 60,000 psi, triaxial compaction shows density variation of ~ 0.03g/cm^3Triaxial compaction is better than isostatic compaction.As the H/D ratio of compact increases, the density variation will be larger.

TRANSVERSE RUPTURE STRENGTH (ksi)PERCENT THEORETICAL DENSITYDensity versus transverse rupture strength for isostatically and triaxially compacted on powder compacts showing the influence of shear stress: no shear; low shear (0-17 ksi); medium shear (17-24 ksi); high shear (34-50 ksi). (1 ksi = 6.9 MPa.)

Density versus transverse rupture strength for isostatically and triaxially compacted on powder compacts showing the influence of shear stressFor the given green density, compacts formed under high shear stress have greater strength.At 90% theoretical density, compacts formed by high shear stress have more than twice the strength of isostatic compacts.Shear stress during compaction increases the green density and the strength.

Triaxial compaction provides improved green density and strength than others.

Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.ISBN 0-13-148965-8. 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.Density as a Function of Pressure and the Effects of Density on Other Properties

(a) Density of copper- and iron-powder compacts as a function of compacting pressure. Density greatly influences the mechanical and physical properties of P/M parts. (b) Effect of density on tensile strength, elongation, and electrical conductivity of copper powder. Source: (a) After F. V. Lenel, (b) IACS: International Annealed Copper Standard (for electrical conductivity).

Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.ISBN 0-13-148965-8. 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.Density Variation in Compacting Metal Powders

Density variation in compacting metal powders in various dies: (a) and (c) single-action press; (b) and (d) double-action press. Note in (d) the greater uniformity of density from pressing with two punches with separate movements when compared with (c). (e) Pressure contours in compacted copper powder in a single-action press. Source: After P. Duwez and L. Zwell.

Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.ISBN 0-13-148965-8. 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.Compacting Pressures for Various Powders

Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.ISBN 0-13-148965-8. 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.Press for Compacting Metal Powder

A 7.3-mn (825-ton) mechanical press for compacting metal powder. Source: Courtesy of Cincinnati Incorporated.

Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.ISBN 0-13-148965-8. 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.Capabilities Available from P/M Operations

Capabilities, with respect to part size and shape complexity, available form various P/M operations. P/F means powder forging. Source: Courtesy of Metal Powder Industries Federation.

Compaction of Metal Powders by Cold Isostatic PressingMetal powder is placed in a flexible rubber mold made of neoprene rubber, urethane, polyvinyl chloride (PVC).The assembly is then pressurized hydrostatically in a chamber, by water.Most common pressure: 400MPa.

Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.ISBN 0-13-148965-8. 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.Cold Isostatic Pressing

Schematic diagram of cold isostatic pressing, as applied to forming a tube. The powder is enclosed in a flexible container around a solid-core rod. Pressure is applied isostatically to the assembly inside a high-pressure chamber. Source: Reprinted with permission from R. M. German, Powder Metallurgy Science, Metal Powder Industries Federation, Princeton, NJ; 1984.

Die insert and linerIt is a removable liner used to minimize too wear, which is fabricated out of hard materials (ex: cemented carbide)Die insert will be in contact with the component.

A liner is similar to this, formed as a coating or hard electroplated layer

Die wall frictionApplied uniaxial load makes the powder to deform and spread laterally.This lateral pressure is against the tooling and creates wall friction.Wall friction reduces powder flow and sliding during compaction.Continual pressure loss with distance from the punch as the powder bleeds off the applied pressure in the form of die wall friction.

Die wall lubricationExternal spray is dispersed on the die wall after every compaction.The die wall lubrication is introduced via seal ring built into the lower punch. As the punch moves to the fill position, it will leave a lubricant film on the die walls.Electrostatic spray with an external dispersion unit.Lubricant can be mixed with powdersMolybdenum disulphide is used as lubricant

Compaction of Metal Powders by other ProcessesRolling: Powder is fed to the roll gap in 2-high rolling mill, and is compacted into a continuous strip at speeds of up to 0.5 m/s.Rolling process carried out at room or at elevated temperature.Common parts: Sheet metal for electrical and electronic components and for coins.

Compaction of Metal Powders by other ProcessesPowder Extrusion:Powder is incased in a metal container and extruded.After sintering, preformed PM parts may be reheated and then forged in a closed die to their final shape.

Sinter forgingApplicable for ceramic partsCeramic deformation takes place at a very slow strain rate.Limited plastic flow capacity (for hot ceramics stress and stain will be low)The cycle time is long.The slow deformation appears like forging.The stress is low and the densification and shaping rates are controlled by diffusional creep.

Powder sinter forgingNo sintering stage is involved.Loose powders are compacted and then hot forged.This is called sinter forging

Advantages of sinter forging

Powder compaction equationsBalshin equation:

Heckel equation:

Powder compaction equations contPanelli and Ambrozio Filho equation:

Ge equation:

Where D- relative density of the compacted material P- applied pressureand others are constants

Powder compaction equation contFindings of Narayanasamy et al. The compaction data were best fitted to the Ge equation for studying the densification behavior of nano composite.The above is Narayanasamy and Jeyasimman work for AA 6061 nano composites reinforced with hybrid (TiC + Al2O3) nano particles.

Powder compaction equations contVan Der Zwan and Siskens equation:

WhereD relative density of the post compacts - relative apparent densityand others are constantsVan Der Zwan and Siskens equation is the well fitted equation according to Narayanasamy and Sivasankaran. It can be used for analyzing the compaction behavior of powders as applicable and useful to P/M industries.

D0

Theory of Plasticity for powder - sinter forgingUniaxial stress state condition:

In the compression of a P/M part, under frictional conditions, the average density is increased. Friction enhances densification and at the same time decreases the height reduction at fracture. The state of stress in a homogeneous compression process is as follows:According to Abdel-Rahman et al.z = eff , r = = 0 (1)where z - axial stress eff - effective stress r - radial stress - Hoop stress.

Theory of Plasticity for powder - sinter forging cont .

- (2)m - mean or hydrostatic stress- (3)0 hoop strain z axial strain D0 initial diameter of the compactsDf contact diameter after deformation

Theory of Plasticity for powder - sinter forging cont .

WhereH0 - initial height of the compactsHf fracture height of the compactsWhen the compression continues, the final diameter increases and the corresponding hoop strain, which is tensile in nature, also increases until it reaches the fracture limit. Once the fracture is initiated, the forming limit strain is the same as the effective strain. It is determined from:

Theory of Plasticity for powder - sinter forging cont .As an evidence of experimental investigation implying the importance of the spherical component of the stress state on fracture according to Vujovic and Shabaik proposed a parameter called a formability stress index which is given by:

This index determines the fracture limit

Theory of Plasticity for powder - sinter forging cont .Plane stress state conditionAccording to Narayanasamy and Pandey, the state ofstress in a plane stress condition is as follows:

where eff is the effective stress,

Where is the Poissons ratio and z is the axial stress in upsetting.

Theory of Plasticity for powder - sinter forging cont .Since the radial stress, r is zero at the free surface it follows from the flow rule that:

m - mean or hydrostatic stress is :

The hoop strain () of the compact is determined by this equation

where Db - bulged diameter of the compactsDc - contact diameter of the compacts Do - initial diameter of thecompacts.

Theory of Plasticity for powder - sinter forging cont .Triaxial stress state conditionAccording to Narayanasamy and Ponalagusamy, The state of stress in a triaxial stress condition is given as follows:

Theory of Plasticity for powder - sinter forging cont .

Theory of Plasticity for powder - sinter forging cont .The effective stress can be determined from the following relation: According to Doraivelu et al.

(or)

for axisymmetric condition

Theory of Plasticity for powder - sinter forging cont .Once we know m and eff ,we can determine the formability stress index (). The formability stress index will tell you to what extend the metal can be forged. is constant for uniaxial compression forging and this value is 0.33.For plane stress and triaxial condition, it has a range of values.For hot forging, the value is very high compared to cold forging.

Theory of Plasticity for powder - sinter forging cont .According to Narayanasamy et al., the formability strain index parameter is defined as follows:

Theory of Plasticity for powder - sinter forging cont .The behaviour of and are same.Narayanasamy et al., proposed pore closure index parameters based on , , n, m and R value.

Referencehttp://www.sciencedirect.com/Alan Lawley and Howard A.Kuhn, Powder Metallurgy Processing, Academic Press, New York.

ReferencesD. Jeyasimman, K. Sivaprasad, S. Sivasankaran, R. Ponalagusamy, R. Narayanasamy, Vijayakumar Iyer Microstructural observation, consolidation and mechanical behaviour of AA 6061 nanocomposites reinforced by -Al2O3 nanoparticles,Advanced Powder Technology, Volume 26, Issue 1, January 2015, Pages 139-148.D. Jeyasimman, R. Narayanasamy, R. Ponalagusamy, V. Anandakrishnan, M. Kamaraj, The effects of various reinforcements on dry sliding wear behaviour of AA 6061 nanocomposites, Materials & Design, Volume 64, December 2014, Pages 783-793.Ilangovan Arun, Muthukannan Duraiselvam, V. Senthilkumar, R. Narayanasamy, V. Anandakrishnan,Synthesis of electric discharge alloyed nickeltungsten coating on tool steel and its tribological studies,Materials & Design, Volume 63, November 2014, Pages 257-262.B. Selvam, P. Marimuthu, R. Narayanasamy, V. Anandakrishnan, K.S. Tun, M. Gupta, M. Kamaraj,Dry sliding wear behaviour of zinc oxide reinforced magnesium matrix nano-composites,Materials & Design, Volume 58, June 2014, Pages 475-481.D. Jeyasimman, S. Sivasankaran, K. Sivaprasad, R. Narayanasamy, R.S. Kambali, An investigation of the synthesis, consolidation and mechanical behaviour of Al 6061 nanocomposites reinforced by TiC via mechanical alloying,Materials & Design, Volume 57, May 2014, Pages 394-404.D. Jeyasimman, K. Sivaprasad, S. Sivasankaran, R. Narayanasamy, Fabrication and consolidation behavior of Al 6061 nanocomposite powders reinforced by multi-walled carbon nanotubes,Powder Technology, Volume 258, May 2014, Pages 189-197.S.C. Vettivel, N. Selvakumar, R. Narayanasamy, N. Leema, Numerical modelling, prediction of CuW nano powder composite in dry sliding wear condition using response surface methodology,Materials & Design, Volume 50, September 2013, Pages 977-996.A.P. Mohan Raj, N. Selvakumar, R. Narayanasamy, C. Kailasanathan, Experimental investigation on workability and strain hardening behaviour of FeCMn sintered composites with different percentage of carbon and manganese content, Materials & Design, Volume 49, August 2013, Pages 791-801.

References cont.M. Srinivasan, C. Loganathan, R. Narayanasamy, V. Senthilkumar, Q.B. Nguyen, M. Gupta, Study on hot deformation behavior and microstructure evolution of cast-extruded AZ31B magnesium alloy and nanocomposite using processing map,Materials & Design, Volume 47, May 2013, Pages 449-455.P. Ravindran, K. Manisekar, R. Narayanasamy, P. Narayanasamy, Tribological behaviour of powder metallurgy-processed aluminium hybrid composites with the addition of graphite solid lubricant, Ceramics International, Volume 39, Issue 2, March 2013, Pages 1169-1182.N. Selvakumar, A.P. Mohan Raj, R. Narayanasamy, Experimental investigation on workability and strain hardening behaviour of FeC0.5Mn sintered composites,Materials & Design, Volume 41, October 2012, Pages 349-357.M. Sumathi, N. Selvakumar, R. Narayanasamy, Workability studies on sintered Cu10SiC preforms during cold axial upsetting, Materials & Design, Volume 39, August 2012, Pages 1-8.P. Ravindran, K. Manisekar, P. Narayanasamy, N. Selvakumar, R. Narayanasamy, Application of factorial techniques to study the wear of Al hybrid composites with graphite addition, Materials & Design, Volume 39, August 2012, Pages 42-54.V. Senthilkumar, A. Balaji, R. Narayanasamy, Analysis of hot deformation behavior of Al 5083TiC nanocomposite using constitutive and dynamic material models, Materials & Design, Volume 37, May 2012, Pages 102-110.V.S. Sreenivasan, D. Ravindran, V. Manikandan, R. Narayanasamy, Influence of fibre treatments on mechanical properties of short Sansevieria cylindrica/polyester composites, Materials & Design, Volume 37, May 2012, Pages 111-121.T. Vigraman, D. Ravindran, R. Narayanasamy, Effect of phase transformation and intermetallic compounds on the microstructure and tensile strength properties of diffusion-bonded joints between Ti6Al4V and AISI 304L, Materials & Design, Volume 36, April 2012, Pages 714-727.

References cont.D.R. Kumar, R. Narayanasamy, C. Loganathan, Effect of Glass and SiC in Aluminum matrix on workability and strain hardening behavior of powder metallurgy hybrid composites, Materials & Design, Volume 34, February 2012, Pages 120-136.M. Srinivasan, C. Loganathan, M. Kamaraj, Q.B. Nguyen, M. Gupta, R. Narayanasamy, Sliding wear behaviour of AZ31B magnesium alloy and nano-composite,Transactions of Nonferrous Metals Society of China, Volume 22, Issue 1, January 2012, Pages 60-65.S. Sivasankaran, K. Sivaprasad, R. Narayanasamy, Microstructure, cold workability and strain hardening behavior of trimodaled AA 6061TiO2 nanocomposite prepared by mechanical alloying, Materials Science and Engineering: A, Volume 528, Issues 2223, 25 August 2011, Pages 6776-6787.S. Sivasankaran, K. Sivaprasad, R. Narayanasamy, P.V. Satyanarayana, X-ray peak broadening analysis of AA 6061100 x x wt.% Al2O3 nanocomposite prepared by mechanical alloying, Materials Characterization, Volume 62, Issue 7, July 2011, Pages 661-672.S. Sivasankaran, K. Sivaprasad, R. Narayanasamy, Vijay Kumar Iyer, Evaluation of compaction equations and prediction using adaptive neuro-fuzzy inference system on compressibility behavior of AA 6061100 xx wt.% TiO2 nanocomposites prepared by mechanical alloying, Powder Technology, Volume 209, Issues 13, 15 May 2011, Pages 124-137.D.R. Kumar, C. Loganathan, R. Narayanasamy, Effect of glass in aluminum matrix on workability and strain hardening behavior of powder metallurgy composite, Materials & Design, Volume 32, Issue 4, April 2011, Pages 2413-2422.V.S. Sreenivasan, D. Ravindran, V. Manikandan, R. Narayanasamy, Mechanical properties of randomly oriented short Sansevieria cylindrica fibre/polyester composites, Materials & Design, Volume 32, Issue 4, April 2011, Pages 2444-2455.M. Srinivasan, C. Loganathan, V. Balasubramanian, Q.B. Nguyen, M. Gupta, R. Narayanasamy, Feasibility of joining AZ31B magnesium metal matrix composite by friction welding, Materials & Design, Volume 32, Issue 3, March 2011, Pages 1672-1676.

References cont.V.S. Sreenivasan, S. Somasundaram, D. Ravindran, V. Manikandan, R. Narayanasamy, Microstructural, physico-chemical and mechanical characterisation of Sansevieria cylindrica fibres An exploratory investigation, Materials & Design, Volume 32, Issue 1, January 2011, Pages 453-461.S. Sivasankaran, K. Sivaprasad, R. Narayanasamy, Vijay Kumar Iyer, Effect of strengthening mechanisms on cold workability and instantaneous strain hardening behavior during grain refinement of AA 6061-10 wt.% TiO2 composite prepared by mechanical alloying, Journal of Alloys and Compounds, Volume 507, Issue 1, 24 September 2010, Pages 236-244.S. Sivasankaran, K. Sivaprasad, R. Narayanasamy, Vijay Kumar Iyer, An investigation on flowability and compressibility of AA 6061100 x-x wt.% TiO2 micro and nanocomposite powder prepared by blending and mechanical alloying, Powder Technology, Volume 201, Issue 1, 12 July 2010, Pages 70-82.G. Naveen Kumar, R. Narayanasamy, S. Natarajan, S.P. Kumaresh Babu, K. Sivaprasad, S. Sivasankaran, Dry sliding wear behaviour of AA 6351-ZrB2 in situ composite at room temperature, Materials & Design, Volume 31, Issue 3, March 2010, Pages 1526-1532.S. Sivasankaran, K. Sivaprasad, R. Narayanasamy, Vijay Kumar Iyer, Synthesis, structure and sinterability of 6061 AA100xx wt.% TiO2 composites prepared by high-energy ball milling, Journal of Alloys and Compounds, Volume 491, Issues 12, 18 February 2010, Pages 712-721.S. Sivasankaran, R. Narayanasamy, T. Ramesh, M. Prabhakar, Analysis of workability behavior of AlSiC P/M composites using backpropagation neural network model and statistical technique, Computational Materials Science, Volume 47, Issue 1, November 2009, Pages 46-59.R. Narayanasamy, V. Anandakrishnan, K.S. Pandey, Effect of molybdenum addition on workability of powder metallurgy steels during cold upsetting, Materials Science and Engineering: A, Volume 517, Issues 12, 20 August 2009, Pages 30-36.S. Natarajan, R. Narayanasamy, S.P. Kumaresh Babu, G. Dinesh, B. Anil Kumar, K. Sivaprasad, Sliding wear behaviour of Al 6063/TiB2 in situ composites at elevated temperatures,Materials & Design, Volume 30, Issue 7, August 2009, Pages 2521-2531.

References cont.R. Narayanasamy, T. Ramesh, M. Prabhakar, Effect of particle size of SiC in aluminium matrix on workability and strain hardening behaviour of P/M composite, Materials Science and Engineering: A, Volume 504, Issues 12, 25 March 2009, Pages 13-23.K. Sivaprasad, S. P. Kumaresh Babu, S. Natarajan, R. Narayanasamy, B. Anil Kumar, G. Dinesh, Study on abrasive and erosive wear behaviour of Al 6063/TiB2 in situ composites, Materials Science and Engineering: A, Volume 498, Issues 12, 20 December 2008, Pages 495-500.R. Narayanasamy, V. Anandakrishnan, K.S. Pandey, Effect of carbon content on instantaneous strain-hardening behaviour of powder metallurgy steels, Materials Science and Engineering: A, Volume 497, Issues 12, 15 December 2008, Pages 505-511.R. Narayanasamy, V. Anandakrishnan, K.S. Pandey, Comparison of workability strain and stress parameters of powder metallurgy steels AISI 9840 and AISI 9845 during cold upsetting, Materials & Design, Volume 29, Issue 10, December 2008, Pages 1919-1925.R. Narayanasamy, K. Baskaran, S. Arunachalam, D. Murali Krishna, An experimental investigation on barreling of aluminium alloy billets during extrusion forging using different lubricants, Materials & Design, Volume 29, Issue 10, December 2008, Pages 2076-2088.K. Baskaran, R. Narayanasamy, Effect of various stress ratio parameters on cold upset forging of irregular shaped billets using graphite as lubricant under plane and triaxial stress state conditions Materials & Design, Volume 29, Issue 10, December 2008, Pages 2089-2103.R. Narayanasamy, V. Anandakrishnan, K.S. Pandey, Effect of carbon content on workability of powder metallurgy steels, Materials Science and Engineering: A, Volume 494, Issues 12, 25 October 2008, Pages 337-342.A.Rajeshkannan, K.S. Pandey, S. Shanmugam, R. Narayanasamy, Deformation behaviour of sintered high carbon alloy powder metallurgy steel in powder preform forging, Materials & Design, Volume 29, Issue 9, October 2008, Pages 1862-1867.

References cont.R. Ponalagusamy, R. Narayanasamy, Finite difference method for analysis of open-die forging of sintered cylindrical billets, Materials & Design, Volume 29, Issue 9, October 2008, Pages 1886-1892.A Rajeshkannan, K S Pandey, S Shanmugam, R Narayanasamy, Sintered Fe-0.8%C-1. 0%Si-0.4%Cu P/M Steel Preform Behaviour During Cold Upsetting, Journal of Iron and Steel Research, International, Volume 15, Issue 5, September 2008, Pages 81-87.R. Narayanasamy, V. Anandakrishnan, K.S. Pandey, Effect of geometric work-hardening and matrix work-hardening on workability and densification of aluminium3.5% alumina composite during cold upsetting,Materials & Design, Volume 29, Issue 8, 2008, Pages 1582-1599.R. Narayanasamy, K. Baskaran, D. Muralikrishna, Some studies on stresses and strains of aluminium alloy during extrusion-forging at room temperature, Materials & Design, Volume 29, Issue 8, 2008, Pages 1623-1632.R. Narayanasamy, V. Senthilkumar, K.S. Pandey, Some features on hot forging of powder metallurgy sintered high strength 4%titanium carbide composite steel preforms under different stress state conditions, Materials & Design, Volume 29, Issue 7, 2008, Pages 1380-1400.R. Narayanasamy, T. Ramesh, K.S. Pandey, Some aspects on cold forging of aluminiumalumina powder metallurgy composite under triaxial stress state condition, Materials & Design, Volume 29, Issue 6, 2008, Pages 1212-1227.R. Ponalagusamy, R. Narayanasamy, R. Venkatesan, S. Senthilkumar,Computer-aided metal flow investigation in streamlined extrusion dies, Materials & Design, Volume 29, Issue 6, 2008, Pages 1228-1239.K. Baskaran, R. Narayanasamy, An experimental investigation on work hardening behaviour of elliptical shaped billets of aluminium during cold upsetting, Materials & Design, Volume 29, Issue 6, 2008, Pages 1240-1265.

References cont.R. Narayanasamy, T. Ramesh, K.S. Pandey, S.K. Pandey, Effect of particle size on new constitutive relationship of aluminiumiron powder metallurgy composite during cold upsetting,Materials & Design, Volume 29, Issue 5, 2008, Pages 1011-1026.A. Syed Abu Thaheer, R. Narayanasamy, Comparison of barreling in lubricated truncated cone billets during cold upset forging of various metals,Materials & Design, Volume 29, Issue 5, 2008, Pages 1027-1035.R. Narayanasamy, T. Ramesh, K.S. Pandey, Some aspects on cold forging of aluminiumiron powder metallurgy composite under triaxial stress state condition, Materials & Design, Volume 29, Issue 4, 2008, Pages 891-903.K. Baskaran, R. Narayanasamy, Some aspects of barrelling in elliptical shaped billets of aluminium during cold upset forging with lubricant, Materials & Design, Volume 29, Issue 3, 2008, Pages 638-661.R. Narayanasamy, V. Senthilkumar, K.S. Pandey, Effect of titanium carbide particle addition on the densification behavior of sintered P/M high strength steel preforms during cold upset forming, Materials Science and Engineering: A, Volume 456, Issues 12, 15 May 2007, Pages 180-188.R. Narayanasamy, T. Ramesh, K.S. Pandey, An experimental investigation on strain hardening behaviour of aluminium 3.5% alumina powder metallurgy composite preform under various stress states during cold upset forming, Materials & Design, Volume 28, Issue 4, 2007, Pages 1211-1223.R. Narayanasamy, N. Selvakumar, K.S. Pandey, Phenomenon of instantaneous strain hardening behaviour of sintered AlFe composite preforms during cold axial forming, Materials & Design, Volume 28, Issue 4, 2007, Pages 1358-1363.S. Malayappan, R. Narayanasamy, G. Esakkimuthu, Barrelling of aluminium solid cylinders during cold upset forging with constraint at both ends, Materials & Design, Volume 28, Issue 4, 2007, Pages 1404-1411.

References cont.R. Narayanasamy, C. Loganathan, The influence of friction on the prediction of wrinkling of prestrained blanks when drawing through a conical die, Materials & Design, Volume 28, Issue 3, 2007, Pages 904-912.S. Malayappan, R. Narayanasamy, K. Kalidasamurugavel, A study on barrelling behaviour of aluminium billets during cold upsetting with an extrusion die constraint at one end, Materials & Design, Volume 28, Issue 3, 2007, Pages 954-961.A. Syed Abu Thaheer, R. Narayanasamy, Barrelling in truncated lubricated zinc cone billets during cold upset forging, Materials & Design, Volume 28, Issue 2, 2007, Pages 434-440.K. Manisekar, R. Narayanasamy, Effect of friction on barrelling in square and rectangular billets of aluminium during cold upset forging, Materials & Design, Volume 28, Issue 2, 2007, Pages 592-598.N. Selvakumar, P. Ganesan, P. Radha, R. Narayanasamy, K.S. Pandey, Modelling the effect of particle size and iron content on forming of AlFe composite preforms using neural network, Materials & Design, Volume 28, Issue 1, 2007, Pages 119-130.R. Narayanasamy, V. Senthilkumar, K.S. Pandey, Some aspects of workability studies on hot forging of sintered high strength 4% titanium carbide composite steel performs, Materials Science and Engineering: A, Volume 425, Issues 12, 15 June 2006, Pages 121-130.R. Narayanasamy, V. Senthilkumar, K.S. Pandey, Some aspects on hot forging features of P/M sintered iron preforms under various stress state conditions, Mechanics of Materials, Volume 38, Issue 4, April 2006, Pages 367-386.R. Narayanasamy, T. Ramesh, K.S. Pandey, Some aspects on strain hardening behaviour in three dimensions of aluminiumiron powder metallurgy composite during cold upsetting, Materials & Design, Volume 27, Issue 8, 2006, Pages 640-650.

References cont.R. Narayanasamy, T. Ramesh, K.S. Pandey, Workability studies on cold upsetting of AlAl2O3 composite material, Materials & Design, Volume 27, Issue 7, 2006, Pages 566-575.R. Narayanasamy, R. Ponalagusamy, R. Venkatesan, P. Srinivasan, An upper bound solution to extrusion of circular billet to circular shape through cosine dies, Materials & Design, Volume 27, Issue 5, 2006, Pages 411-415.K. Manisekar, R. Narayanasamy, S. Malayappan, Effect of friction on barrelling in square billets of aluminium during cold upset forging, Materials & Design, Volume 27, Issue 2, 2006, Pages 147-155.R. Ponalagusamy, R. Narayanasamy, P. Srinivasan, Design and development of streamlined extrusion dies a Bezier curve approach, Journal of Materials Processing Technology, Volume 161, Issue 3, 30 April 2005, Pages 375-380.R. Narayanasamy, T. Ramesh, K.S. Pandey , An investigation on instantaneous strain hardening behaviour in three dimensions of aluminiumiron composites during cold upsetting, Materials Science and Engineering: A, Volume 394, Issues 12, 15 March 2005, Pages 149-160.R. Narayanasamy, T. Ramesh, K.S. Pandey, Some aspects on workability of aluminiumiron powder metallurgy composite during cold upsetting, Materials Science and Engineering: A, Volume 391, Issues 12, 25 January 2005, Pages 418-426.N Selvakumar, R Narayanasamy, Phenomenon of strain hardening behaviour of sintered aluminium preforms during cold axial forming, Journal of Materials Processing Technology, Volume 142, Issue 2, 25 November 2003, Pages 347-354.R Narayanasamy, P Srinivasan, R Venkatesan, Computer aided design and manufacture of streamlined extrusion dies, Journal of Materials Processing Technology, Volume 138, Issues 13, 20 July 2003, Pages 262-264.

References cont.S. Malayappan, R. Narayanasamy, Some aspects on barrelling in aluminium solid cylinders during cold upset forging using a die with constraints, Journal of Materials Processing Technology, Volume 135, Issue 1, 1 April 2003, Pages 18-29.R. Narayanasamy, R. Ponalagusamy, K.R. Subramanian, Generalised yield criteria of porous sintered powder metallurgy metals, Journal of Materials Processing Technology, Volume 110, Issue 2, 19 March 2001, Pages 182-185.R Narayanasamy, S Sathiyanarayanan, R Ponalagusamy, Uniaxial tensile behaviour of ZM-21 magnesium alloy at room temperature, Journal of Materials Processing Technology, Volume 102, Issues 13, 15 May 2000, Pages 56-58.R Narayanasamy, S Sathiyanarayanan, R Ponalagusamy, A study on barrelling in magnesium alloy solid cylinders during cold upset forming, Journal of Materials Processing Technology, Volume 101, Issues 13, 14 April 2000, Pages 64-69.R Narayanasamy, K.S Pandey, A study on the barrelling of sintered iron preforms during hot upset forging, Journal of Materials Processing Technology, Volume 100, Issues 13, 3 April 2000, Pages 87-94.R. Narayanasamy, R. Ponalagusamy, A mathematical theory of plasticity for compressible powder metallurgy materials Part III, Journal of Materials Processing Technology, Volume 100, Issues 13, 3 April 2000, Pages 262-265.R Narayanasamy, R Ponalagusamy, A mathematical theory of plasticity for the upsetting of compressible P/M materials, Journal of Materials Processing Technology, Volume 97, Issues 13, 1 January 2000, Pages 107-109.R. Narayanasamy, R. Ponalagusamy, A mathematical theory of plasticity for compressible powder metallurgy materials Part II, Journal of Materials Processing Technology, Volume 97, Issues 13, 1 January 2000, Pages 110-113.

References cont.R. Narayanasamy, R. Ponalagusamy, A mathematical theory of plasticity for compressible P/M materials, Journal of Materials Processing Technology, Volume 86, Issues 13, 15 February 1999, Pages 159-162.R Narayanasamy, KS Pandey, Some aspects of work hardening in sintered aluminiumiron composite preforms during cold axial forming, Journal of Materials Processing Technology, Volume 84, Issues 13, 1 December 1998, Pages 136-142.A.J.R. Inigoraj, R. Narayanasamy, K.S. Pandey, Strain-hardening behaviour in sintered aluminium3.5% alumina composite preforms during axial compression with and without annealing, Journal of Materials Processing Technology, Volume 84, Issues 13, 1 December 1998, Pages 143-148.R. Narayanasamy, K.S. Pandey, Salient features in the cold upset-forming of sintered aluminium3.5% alumina powder composite performs, Journal of Materials Processing Technology, Volume 72, Issue 2, 7 December 1997, Pages 201-207.R. Narayanasamy, K.S. Pandey, Phenomenon of barrelling in aluminium solid cylinders during cold upset-forming, Journal of Materials Processing Technology, Volume 70, Issues 13, October 1997, Pages 17-21.R. Narayanasamy, R.S.N. Murthy, K. Viswanatham, G.R. Chary, Prediction of the barreling of solid cylinders under uniaxial compressive load, Journal of Mechanical Working Technology, Volume 16, Issue 1, February 1988, Pages 21-30.Role of hybrid reinforcement on microstructural observation, characterization and consolidation behavior of AA 6061 nanocomposite, Advanced Powder Technology, Article in Press (2015).

Thank you

Thank you